Awesome Endpoints

New endpoints:
 * get_children (for menu building)
 * get_siblings (for menu building)
 * get_parents (for menu building)
 * get_published_draft (for previews)
 * get_draft (for previews)
 * get_recent_drafts (for previews)

Adds "absolute_slug" to response since you need the full slug to access it via slug. For instance if you have a parent page "foo" with a child page "bar" you need to access `?slug=foo/bar`.

This also allows you to pass login credentials for private blogs.

This additions have been live for almost a year.